Many state-of-the-art processing devices, such as tablet personal computers (PCs) or other processing devices, permit a user to provide input as digital ink. The digital ink may include one or more handwritten strokes, which a processing device may display as ink while the one or more handwritten strokes are being input. A handwritten stroke may begin when a writing instrument lands on a writing surface, and may end when the writing instrument is lifted off the writing surface. The writing surface may include a display screen, which may further include a digitizer, and the writing instrument may be an electronic or non-electronic pen, a stylus, a user's own finger, a pointing device, such as, for example, a computer mouse, or another writing instrument.
A user may input one or more handwritten strokes, as digital ink, to form a two-dimensional structure. The two-dimensional structure may include a mathematical expression, a chemical formula, textual characters, numbers, or other two-dimensional structures.
Recognizers for recognizing a digital ink two-dimensional structure, such as, for example, a mathematical expression, may include a structure recognizer and a symbol recognizer, which may be trained in a unified manner. That is, training of the structure recognizer and the symbol recognizer may be performed together.
Existing recognizers may produce a recognition result having a misrecognized portion. The user may attempt to correct the misrecognized portion by selecting the misrecognized portion of the recognition result. In at least one existing recognizer, the user may attempt to correct a misrecognized character of the recognition result by selecting the digital ink corresponding to the misrecognized character. Selecting the misrecognized portion of the recognition result, or selecting the digital ink corresponding to the misrecognized character in the recognition result, may cause one or more alternates to be displayed. The user may select one of the one or more alternates, thereby causing the misrecognized character to be replaced with the selected one of the one or more alternates without re-recognizing the input digital ink. One existing recognizer permits the user to type a correct character from a keyboard when the correct character is not among the displayed one or more alternates.